Figure 5.

Shown is a schematic model used to explain the genomic relationships of synchronous breast cancers arising from a common progenitor. In the first model, the progenitor breast cancer cell 1 (left) contains the “core” genomic information, and genomic divergence during tumor growth leads to synchronous tumors possessing related genomic signatures (shown as a different gray tone). The expansion of clones from this common progenitor, through either selection of the microenvironment or karyotypic viability, results in clones that will accumulate unique genomic changes. The second model implicates the presence of a progenitor breast cancer cell 2 shown in gray, also possessing the “core” genomic information for breast cancers. Collectively, it can be seen that tumors (1 and 2) can evolve independently from the progenitor cell with no common lineage, but may possess common changes.